This application relates to the art of workpiece guide mechanisms and, more particularly, to such mechanisms for guiding elongated generally cylindrical workpieces moving longitudinally along their axes.
Elongated generally cylindrical workpieces such as rods or tubes are commonly guided as they are moved longitudinally into machining, grinding, peeling or straightening devices. Such workpieces commonly have bends or out-of-round eccentric cross-sectional configurations along their length. In view of the bends and eccentricities, it is necessary that the workpiece guides be capable of floating or breathing so that the workpieces will continue to be fed along the same axis throughout their length.
Workpiece guide apparatus of the type described is also subject to severe vibrations which are imparted to the workpieces by the machine tools through which the workpieces are fed and the guide apparatus must absorb these vibrations. Desigining a workpiece guide apparatus with a minimum cross-sectional size makes it possible to place the guide apparatus within or very close to the station where work is performed on the workpieces. However, this design reduces the rigidity of the guide apparatus, and increases the distance between workpiece guides and their adjusting means so that the problem of dampening vibrations is magnified.
One known type of workpiece guide apparatus is disclosed in German patent no. 2,156,125 and includes a tubular support body having a passage through which elongated generally cylindrical workpieces move longitudinally along an axis substantially coincidental with the axes of the workpieces. Four spaced-apart shafts are rotatably mounted in the support body parallel to the axis along which the workpieces move. Each shaft has a workpiece guide extending inwardly toward the axis for supporting and guiding the workpieces. The other ends of the shafts have chain wheels connected with a common chain and at least one shaft has an adjusting lever connected with a fluid cylinder. Operation of the cylinder swings the adjusting lever to rotate the shaft and its chain wheel which simultaneously rotates all of the chain wheels and shafts through the common chain. The elastic or yieldable support of the adjusting lever against the fluid cylinder provides a floating or breathing yieldable movement of the workpiece guides. However, all of the workpiece guides will yield in unison with such an arrangement and the workpiece guides can come out of contact with the workpiece. Also, the workpiece guides extend over the entire length of the guide apparatus and workpieces at the entrance or outlet end of the guide apparatus are not always guided at a plurality of spaced locations around their entire circumference. For example, a curved or bent workpiece will be guided at only two or three longitudinally-spaced areas by the workpiece guides. Thus, centering of the workpieces is not assured, and dampening of vibrations in the workpieces is not constantly assured at the outlet end of the guide apparatus.